This invention has to do with an improved beer-dispensing system and apparatus and is particularly concerned with an apparatus for dispensing beer from kegs at low temperature and with a minimum of foam.
Beer, as herein used, refers to anyone of those carbonated alcoholic malt beverages that are commonly called beer, ale and stout.
In most commercial establishments where beer is served, the beer is supplied in barrels or kegs. The kegs of beer are stored and let to cool in refrigerated cold rooms that are provided in most commercial establishments to store foodstuffs and beverages for immediate access and use. For practical reasons, the temperature in cold rooms must be well above freezing (32.degree. F.) and is typically sought to be maintained between 40.degree. F. and 45.degree. F. Accordingly, the beer, in kegs, stored in cold rooms is cooled to between 40.degree. F. and 45.degree. F. Under most favorable conditions, the beer is cooled to 40.degree. F.
The beer that is chilled to 40.degree. F. is dispensed from normally closed selectively operable beer-dispensing valves that are located at serving stations that are remote from the cold rooms. The dispensing valves are normally carried at the upper ends of elongate vertically extending dispensing towers that are mounted atop and project upwardly from bar tops or counters so that the valves occur in spaced relationship above the counters and such that serving glasses and the like can be conveniently positioned on the counters, below the valves, to receive beer issuing from the valves.
The beer is delivered from the kegs to the dispensing valves through elongate beer delivery lines with upstream ends that are connected with taps that are engaged in the kegs. The beer lines extend from the kegs and from within the cold rooms and extend to the dispensing stations where their downstream ends are suitably connected with the dispensing valves.
The beer lines are most often established of 3/4"-ID plastic tubing that is especially formulated and approved for handling alcoholic beverages. The beer lines vary in length from about 15' or 20' to in excess of 100'. The downstream ends of the beer delivery lines connect with the upstream ends of equalizer or balance lines made of similar plastic tubing but which is smaller in inside diameter than the beer lines. For example, the balance lines are established of 1/4"-ID tubing. The balance lines vary in length between 9' and 15'. Typically, the downstream ends of the balance lines connect with the upstream ends of 1/4"-ID stainless steel connector tubes that project from the lower ends of the towers and that extend up through the towers and connect with the valves.
In practice, beer is driven and caused to move from the kegs through the beer lines and to the valves by gas pressure. To this end, suitable high-pressure motive gas supplies are provided to introduce gas under desired pressure, into the kegs. The motive gases most commonly used are air, carbon dioxide, nitrogen, and combinations of those gases. The gases are most commonly provided in compressed gas cylinders that are stored in the cold rooms and are conducted from the cylinders into the kegs, to the taps, through gas lines. Pressure regulators are provided in the gas lines to control the pressure of the gas in the kegs. Due to friction losses in the systems, the pressure at which the gases are introduced into the kegs is adjusted and set so that beer dispensed from the dispensing valves flows at a set desired rate. The usual rate at which beer is dispensed from the dispensing valves is between 2 and 4 ounces per second.
It is important to note that when the gas (CO.sub.2) that is entrained in beer is let or caused to separate from the beer, it creates foam composed of gas-filled bubbles of beer. When beer is dispensed into a serving glass, the foam generated by the escape of gas is seen to rise to the top of the beer. The foam is rather stable and is such that it breaks down at such a slow rate that it must often be directed to waste by letting it overflow and/or pouring it off from the glasses in which the beer is to be served. If beer is not properly handled, in excess of 50% of the beer can be lost to waste, in the form of foam. It is to be noted that the gas that is entrained in beer imparts into the beer that tongue and pallet stimulating sensation that consumers of beer desire and that is sometime called its "life." As gas escapes from beer and is carried away in the form of foam, the beer loses its "life" and becomes what is referred to as "flat" and unpalatable, at a rapid rate. Thus, beer in a glass containing a large volume of foam is likely to have lost so much gas that it is flat and of inferior character, if not unmerchantable.
The gas in beer is quite unstable and is such that if let or caused to rapidly expand, as result of rapid thermal heating of the beer or as a result of a rapid reduction of pressure on the beer, it will immediately reach or attain a highly excited state in which adjacent expanding bubbles of beer displace the liquor of the beer and continue to establish ever-increasing larger bubbles of gas that cannot be contained by and that seek to escape or separate from the beer. Once the above gas-separating process starts and/or is put into motion, it does not stop immediately when the temperature and/or pressure on the beer becomes stabilized, but continues until the kinetic energy created by the process is spent and the beer returns to a suitable quiet state.
As the temperature of beer is lowered, the gas entrained therein contracts and becomes more stable and less likely to separate from the beer. Accordingly, it is desirable to chill beer to as low a temperature (above freezing) as possible when it is dispensed.
It is also to be noted that the above-noted gas-release process resulting from rapid rises in temperature and/or rapid drops in pressure will occur at any temperature, though the severity of the process decreases as the temperature of the beer is decreased.
Next, it is to be noted that beer stored in kegs is maintained under pressure to maintain the gas compressed and entrained in the beer. When the pressure on the beer is suddenly released or reduced, as when the dispensing valves are opened, the gas entrained therein is let to expand and the above-noted gas-releasing process is set into motion. When the dispensing valves in beer-dispensing systems of the nature and character referred to above are opened, the pressure on the beer, immediately downstream from the valves, is released and the gas entrained in the beer commences to release. The foregoing results in the beer being driven or blasted through and out of the dispensing valves with and by the gas released immediately downstream thereof. As a result of the foregoing, the prior art has resorted to the provision and use of the above-noted balance lines. The balance lines, which are smaller in inside diameter than the beer delivery lines, function to cause the drop in pressure that occurs when the dispensing valves are open to occur in the downstream end portions of the beer delivery lines. The balance lines are of sufficient length so that as the beer and free gas (that is released in the beer lines) enters the upstream ends thereof and continues to flow therethrough it become sufficiently quite so that the freed gas is reabsorbed by the beer by the time the beer reaches and flows through and from the dispensing valves. While the noted balance lines are effective to eliminate or greatly reduce those adverse effects that result from a rapid release of pressure on beer, they have little or no effect in preventing the adverse effects that result from progressive warming of the beer and expansion of the gas contained therein. As a result of the foregoing, while the provision and use of the above-noted balance lines attains beneficial end results, they are not wholly effective to prevent the escape of gas from beer flowing therethrough and the generating of excess foam that is discharged through and from the dispensing valves with the beer that is dispensed.
It is to be noted that the portions of the beer lines that extend from the cold rooms to the dispensing stations and the balance lines, connecting tubes and valves are exposed to the ambient temperatures of the establishments in which the beer-dispensing systems are installed. Accordingly, though the beer might be cooled to 40.degree. F. when it enters the beer lines, it will (if not maintained cooled) warm and heat to temperatures beyond which the beer can be satisfactorily dispensed. To this end, the prior art has resorted to the provision and use of what the art refers to as "glycol machines or systems" that serve to prevent excess warming of beer as it flows through beer-dispensing systems. The above-referred to glycol systems typically include refrigerated glycol heat exchanger units within the cold rooms and in which a glycol (anti-freeze) solution is chilled. The systems next include an elongate glycol delivery line with an upstream end that connects with the heat exchanger unit and that extends longitudinally of the beer lines in heat-conducting contact therewith; and a glycol return line continuing from the downstream ends of the glycol delivery line and that extends longitudinally of the beer line, in heat-conducting contact therewith and that has a downstream end that connects with the heat exchanger unit. Pump means are included to cause the glycol solution to continuously recirculate through the glycol lines and the heat exchange unit. The related beer lines and glycol lines are contained within an elongate thermal-insulating jacket structure. The assembled beer and glycol lines and the thermal-insulating jacket establish what is commonly referred to as a "trunk line."
In practice, the glycol delivery and return lines are commonly extended to run parallel with and adjacent to the balance lines.
The glycol lines are established of the same plastic tubing as the beer delivery lines and balance lines.
While the above-noted glycol systems would appear to establish good and effective heat exchanger means that would work to further chill or prevent warming of beer flowing through the beer lines and balance lines, in some instances they do not prevent warming of the beer but simply slow the rate at which it warms. This is due to the fact that the plastic tubing of which the several lines are established has an extremely low coefficient of heat conductivity. Further, while the glycol and beer-conducting lines contact each other, that contact seldom amounts to more than thin line contact. Further, due to space limitations and the like, the thermal-insulating jackets used in trunk lines are not so efficient a barrier of heat to prevent some heat from entering the trunk lines and reaching the beer delivery lines. As a result of the foregoing, when, for example, glycol chilled to 25.degree. F. is conducted through 100' of glycol line in a 50' long trunk line and beer, at 40.degree. F., is conducted through a related 50' of beer line within that trunk line, the temperature of the glycol, as it is returned to the glycol heat exchanger, is likely to be warmed to no more than 27.degree. F. and the beer, at the downstream end of the beer line is likely to be warmed to an excess of 40.degree. F. Accordingly, the noted glycol systems often do no more than to notably slow the rate at which beer warms as it flows through related beer lines, they do not necessarily and in all instances chill or prevent warming of the beer. That warming of the beer that often does take place and results in expansion of the gas entrained in that beer to render the gas highly unstable and very likely to commence to separate from the beer.
The above-noted warming of beer as it moves through the noted trunk lines is accelerated somewhat as it advances through related balance lines to dispensing valves. This further unstabilizes the gas in the beer and renders it such that when the dispensing valves are opened, and the pressure on the beer is released, gas commences to escape from the beer, generating foam which is dispensed from the dispensing valves together with that beer which is not foamed.
In the more recent past, the prior art has resorted to the provision and use of high efficiency heat exchangers connected with and between the downstream ends of the beer delivery lines and the upstream ends of related balance lines and through which chilled glycol is conducted to chill and reduce the temperature of the beer from, for example, 40.degree. F. to 30.degree. F. The beer chilled to 30.degree. F. is then conducted into and through the balance lines and thence through and from the dispensing valves. When chilled to 30.degree. F. as noted above, the gas in the beer is considerably more stable than it was when the beer was 40.degree. F. However, if the beer warms two or three degrees as it advances through the balance lines, and the gas expands accordingly, the gas will escape and foam will be generated. The amount of foam that is generated under such circumstances is denser or less in volume and is colder, but it is nonetheless generated and continues to expand.
The most effective and efficient heat exchangers referred to in the foregoing are cold plate type heat exchangers that include cast aluminum bodies with stainless steel beer- and glycol-conducting coils therein that are suitably connected with the beer and balance lines and with the glycol delivery and return lines. The aluminum bodies are suitably jacketed with thermal insulation to block the entry of ambient heat (72.degree. F.)into the bodies.
Other chilling means for lowering the temperature of beer before it is conducted into and through balance lines in beer-dispensing systems have included common refrigerated bath-type chillers. Those heat exchangers have proven to be notably less efficient and effective than the above-noted cold plate type heat exchangers.
In another beer-dispensing system provided by the prior art, the balance lines are established of stainless steel and are arranged within compartments or chambers within related dispensing tower structures mounted atop counters and that carry the dispensing valves. The chilled glycol of related glycol systems is circulated in and through the chamber and about the balance lines to chill the beer within and flowing through the balance lines to the dispensing valves. While this form of heat exchange means is effective to chill beer that is let to stand in the balance lines, the glycol is incapable of carrying off heat from the beer (through the walls of the balance lines) at a sufficient rate to notably chill beer that is continuously flowing through the balance lines at a rate of, for example, 4 ounces per second. As a result of the above, the first-to-be-served beer (that has been let to stand and to chill in the balance lines)is suitably chilled. Thereafter, as the chilled beer is dispensed and new and warm beer enters the balance lines to replace it, the temperature of the beer being dispensed warms at a notable rate and the dispensing of the beer must be delayed after each serving of beer has been dispensed, if beer, at the desired low temperature, is to be served without notable foaming.
In addition to the above, when warm beer enters the balance lines in the last-noted heat exchanger means and combines with previously chilled beer in the balance lines, a portion of the chilled beer is warmed by the incoming beer, When that chilled beer is thus warmed, the gas therein expands and the previously noted gas release process takes place. As a result of the foregoing, when beer is dispensed from systems including the last-noted form of heat exchanger means, the beer dispensed is seldom uniform, that is, it intermittently runs clear and free of foam and then runs laded with foam for short periods of time.
The foregoing led us to recognize the need for heat exchanger means related to the balance lines in beer-dispensing systems that operates to prevent any elevation in temperature of beer and the expansion of gas entrained therein as the beer moves longitudinally downstream through the balance lines; and, a means that preferably operates to effect progressive chilling of the beer as it moves through the balance lines and to thereby cause constriction and increased stabilization of the gas entrained therein.
It was also recognized that a heat exchanger means of the character referred to above should be such that it lowers the temperature of beer flowing through the balance line substantially continuously as it moves therethrough at a rate of at least 40 ounces per minute and such that beer can be substantially continuously intermittently dispensed at a rate of no less than three 10-ounce serving per minute, without the loss of appreciable gas from the beer and the generating of appreciable amounts of foam.